GB825004A - Reinforced resinous structural material - Google Patents

Abstract

825,004. Sheet material composed of agglutinated fibres or threads; laminates. MINNESOTA MINING & MANUFACTURING CO. Sept. 9, 1955 [Sept. 9, 1954], No. 11409/55. Class 140. A method of producing resinous sheet material reinforced with glass filaments comprises combining continuous glass filaments treated to render the surface resin-receptive, into a flat compact layer in substantial linear alignment; passing the layer under even tension through a bath of solvent-free liquid resin binder composition which is rapidly thermosetting at a temperature higher than that of the bath until the layer is saturated; squeezing the resultant resin-impregnated web and solidifying the resin composition sufficiently to provide a flat flexible non-porous sheet the resin component of which is potentially fusible and heat-curable to a hard tough resin finely bonded to the filaments. Glass filaments may be employed in the form of narrow beams, yarn, tow or rovings, each strand or bundle consisting of a large number of individual filaments. The filament bundles may be untwisted or lightly twisted. The filaments may be drawn from the spinneret orifices by rapidly rotating drums, treated with a primer composition, grouped into bundles and condensed into a dense flat layer and then heated by radiant heated bars just prior to contact with the resin. After passing through the resin bath the web is passed through squeeze rolls to provide complete wetting of the glass surfaces by resin, and then immediately treated to solidify the resin (e.g. by cooling with a chilled air blast). Layers of the sheet may be superimposed in the form of multiple laminations which may be lightly bonded together to produce pre-forms from which desired end-products may be formed by pressuremoulding or otherwise. Specified resins are epoxide resins formed, e.g. by reaction of epichlorohydrin with bisphenol A in the presence of caustic soda; or epichlorhydrin with glycerol in presence of boron trifluoride with subsequent addition of alkali. Curing agents and catalysts may be incorporated in the resin composition. As shown (Fig. 1) webs of untwisted or lightly twisted filament bundles are brought together between guide rollers 10 and 11 and condensing comb 12 and over a series of uneven bars 13 to form a dense flat permeable sheet 14 of continuous glass filaments. The sheet passes between radiant heaters 15, through trough 16 containing the resinous composition 17 in liquid fused form, then through a three roll calender, after which it is cooled by fans 20 and wound up on drum 21 together with a temporary separation sheet 22 from supply roll 23. Fig. 2 shows sheet material according to the invention, wherein the individual filaments 24 are surrounded by resinous composition 25, the approximate location of the filament bundles as initially introduced into the sheet being indicated by boundary lines 26. Specification 619,674 is referred to.